Handhole plug



June 1966 E. P. WORTHEN ETAL 3,254,783

HANDHOLE PLUG Oriinal Filed Aug. 22, 1960 "Q S q w mvsmoxs fuyene Par/er Worf/ren Lk John Henry Sfe/l/ng ATTORNEY United States Patent 3,254,788 HANDHOLE PLUG Eugene Porter Worthen, Braintree, and John Henry Stelling, South Yarmouth, Mass, assignors, by mesne assignments, to Bethlehem Steel Corporation, a corporation of Delaware Application Mar. 8, 1965, Ser. No. 437,962, which is a division of application Ser. No. 51,043, Aug. 22, 1960. Divided and this application June 16, 1965, Ser. No.

2 Claims. or. -39

This application is a division of copending application Serial No. 437,962, filed March 8, 1965, for Handhole Plug, which latter application is a division of copending application Serial No. 51,043, filed August 22, 1960, for Tubesheetless Buttwelded U-Tube Type Combined Steam Generator and Non-Condensa-ble Gas Extractor.

The present invention relates broadly to a plug for a header. More particularly, the present invention relates to a handhole plug for a pipe header.

As disclosed in the above-mentioned parent application Serial No. 51,043, the present invention is particularly useful in association with pipe headers in steam generators operating at high temperatures and pressures. Such steam generators may, for instance, receive primary saturated steam from a nuclear reactor of the boiling water type and raise secondary steam from feed heated by the primary steam, the secondary steam being used for example in power plants. These steam generators may receive primary saturated steam from the reactor at a pressure of 1000 p.s.i.a. (approximately 545 F.) to generate secondary saturated steam at a pressure of 600 p.s.i.a. (approximately 486 F.), the primary steam condenate leaving at about 545 F. and the secondary feed entering at about 486 F. These figures are given by way of illustration only.

Steam generators of the type above described have a number of tubes in which the high-temperature, high pressure heating medium (the primary saturated steam from the nuclear reactor) is circulated. As disclosed in the above-mentioned parent application Serial No. 51,043, these tubes may be fed from a header and may discharge to a header, replacing the conventional tube sheet. From time to time, while the steam generator is in service, leaks may occur in some of the tubes. For reasons of economy, it is desirable to be able to quickly secure access to the interiors of the defective tubes to plug them, thus removing the defective tubes from service and stopping leakage therethrough without taking the steam generator out of service for any extended period of time. Thereafter, when convenient, the defective tubes can be replaced with new tubes. conventionally, handhole plugs in the headers opposite the tubes are provided. These handhole plugs are removed to obtain access to the interiors of their respective tubes, and are replaced to close the header. One problem is to provide a handhole plug which can withstand the high pressure of the primary saturated steam in the header thereby to provide a seal in the header wall.

One of the objects of this invention is to provide an improved handhole plug.

Another object of this invention is to provide an improved handhole plug adapted to withstand high pressures and yet capable of being quickly and easily removed and installed in a header.

Other and further objects of this invention will become apparent during the course of the following description.

We have discovered that the foregoing objects can be attained by providing handhole plugs of special configuration.

Referring now to the drawings, in which like numerals represent like parts in the several views:

FIGURE 1 represents a transverse section of a header showing the handhole plug.

FIGURE 2 represents a longitudinal View of the header of FIGURE 1, partially broken away at the centerline showing the handhole plug.

When a tube 12 develops a detect, the openings in four-element fittings 10 corresponding to the defective tube 12 can be plugged, permitting continued operation of the steam generator until such time as it is convenient to replace the defective tube 12. The present invention permits easy access through header 6 to the proper hole of the particular four-element fitting 10 for quick installation of a plug (not shown).

Header 6 is provided with a number of internally threaded collars 4t) welded thereto, each of said collars 40 being located opposite a pair of four-element fittings 10 as shown in FIGS. 1 and 2. To close the openings in header 6, diaphragms 41 are seal welded thereto at 42. Expansion ring 43 on diaphragm 41 prevents seal weld 42 from cracking as it cools. Handhole plug 13 is externally threaded to mate with collar 40, and when fully inserted, bears against diaphrgam 41. Thus, in this design, tightness is maintained by diaphragm 41 and seal weld 42, and the holding power is provided by the handhole plug 13. Means (not shown) will be provided to prevent handhole plug 13 from unscrewing in service. To open the header 6 to gain access to the interior of any particular four-element'fitting 10, handhole plug 13 is unscrewed, seal weld 42is cut, and diaphragm 41 is removed.

We claim:

1. Removable sealing means for an opening in a header comprising a seal diaphragm in said opening seal welded to said header, an expansion ring formed in said seal diaphragm adjacent the outer edge thereof, and a threaded plug screwed into said opening end bearing against said seal diaphragm.

2. In combination with an opening in a header and an internally threaded collar secured to said header in registry with said opening, removable sealing means comprising a seal diaphragm in said opening seal welded to said header, an expansion ring formed in said seal diaphragm adjacent the outer edge thereof, and a broadbased threaded plug screwed into said collar, the broad base of said plug bearing against substantially all of said seal diaphragm within said expansion ring.

References Cited by the Examiner UNITED STATES PATENTS 1/1958 Alt 22046 5/1959. Tinker 22039 THERON E. CONDON, Primary Examiner.

G. T. HALL, Assistant Examiner. 

2. IN COMBINATION WITH AN OPENING IN A HEADER AND AN INTERNALLY THREADED COLLAR SECURED TO SAID HEADER IN REGISTRY WITH SAID OPENING, REMOVABLE SEALING MEANS COMPRISING A SEAL DIAPHRAGM IN SAID OPENING SEAL WELDED TO SAID HEADER, AN EXPANSION RING FORMED IN SAID SEAL DIAPHRAGM ADJACENT THE OUTER EDGE THEREOF, AND A BROADBASED THREADED PLUG SCREWED INTO SAID COLLAR, THE BROAD BASE OF SAID PLUG BEARING AGAINST SUBSTANTIALLY ALL OF SAID SEAL DIAPHRAGM WITHIN SAID EXPANSION RING. 